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Mrs. Harriss slides:IgneousMetamorphicSedimentary
Earth ScienceIgneous Rocks
TodayIgenous rocksIntrusiveExtrusiveCrystal sizeTextureComposition
Igneous RockA rock made from the solidification of cooled magmaRocks melt = magmaMagma cools = igneous rock
What makes rock melt?
Making MagmaTemperature 1,000-2,000 FoDifferent minerals melt at different temperatures (like cheeses)
PressureHigher pressure requires higher temperatures to melt
Water and/or Carbon DioxideThese lower the pressure which lowers the temperature required to melt
Partial MeltingCertain minerals will melt before others based on their chemical compositionLike having butter, chocolate, and cheese in a pot what melts first?
Types of IgneousIntrusiveForm below the surface
ExtrusiveForm on the surface
Cool It!Rate of cooling determines size of the crystals
Slow = largeIntrusive
Fast = smallExtrusive
Ever made rock candy?
Slow CoolerLarge crystals
Course texture
Intrusive or extrusive?
Quick CoolerSmall crystals
Fine texture
Intrusive or extrusive?
Can it be both?
Absolutely!When magma cools quickly at first and then slower it makes both crystal sizes.
This is called porphyritic
Other texturesGlassyVesicular
IntrusiveMagma pushed into existing rock and cools
Intrusive
ExtrusiveLavaMagma on Earths surface
PyroclastsAshes to rocks, erupted
Pyroclastic flowHot, dry ash, rock, and gasses
CompositionFelsicLots of silicaLight in colorMaficIron & magnesiumDarker in color(sometimes has ferromagnesium minerals)Intermediate rocks are in between felsic and mafic.
VocabTextures:FineCoursePorphyriticGlassyVesicularCompositionFelsicMaficIntermediate
What do you callA rock has cooled quickly and is dark in color
What do you callA rock has cooled quickly and is dark in color
What do you callA rock has cooled slowly and is light in color
What do you callA rock has cooled slowly and is light in color
What do you callA rock has cooled fast then slow and is light and dark in color
What do you callA rock has cooled fast then slow and is light and dark in color
This week6-2 quizUnit 6 discussionUnit 6 assignment7-2 quiz7-2 quiz
Next classMetamorphicSedimentary
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*Metamorphic RockWhat is it?
When does it happen?
Where do they occur?
Types of metamorphism
*Metamorphic Rock
Meta & morph = change shape
Rocks changed by heat, pressure, and fluids
*Making Metamorphic RockTwo rules for changes:
Below the surface
Solid state
*Metamorphic HeatAt least 250 Co
Geothermal gradientEarth gets hotter by 25 Co for every km down
Magma = Contact metamorphism
Changes bonding structure
*Metamorphic Pressure
Pressure: need 2 kilobars
Depth Add a kbar for every 3-ish km down
Convergent and transform boundaries = regional metamorphism
Strains bonds, some break, more compact structure
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*
*Metamorphic Chemical Fluid
Fluid carrying dissolved ions
Magma chamber
Ridge vents
Changes minerology
*After metamorphismRecrystallizationCrystal size changes
CompactionPore space reduced
Foliation (not always)Parallel platy grains
*Slate
*Schist
*Gneiss
Sedimentary RockRocks formed by one of 3 processes:Physical processesPlants and animalsChemical processes
Sedimentary: Physical ProcessFormed by the physical breakdown of pre-existing rocksEroding agents like water, wind, ice
Transported (load), deposited, lithification (next slide)
Clastic rocks
Lithification- sediment changes to rock
Compaction- increased pressure & temp, removes water
Cementation- any spaces become filled by minerals out of solution
Mineralogic change- some break down, others change
Sedimentary: Physical Process
Sandstone
Sedimentary: Plants & AnimalsMade of plants and/or animalsExamples:Shells, bacteria, compressed plants
Organic sedimentary rock
Oil Shale- Tropical plants, compressed
Stromatolites- made by algae
Sedimentary: Chemical ProcessRocks made of crystals from solutionChemicals in water, water evaporates, crystals growCalled evaporite
Chemical Sedimentary Rocks
Halite- a.k.a. salt
Fossils
Looking Ahead:Unit 7 AssignmentsPart 1 is a unit testPart 2 is a short report
Next week: ores & mining